Device for controlling the feeding force at rock-drilling

ABSTRACT

A device for controlling the feeding force at rock-drilling is disclosed, comprising an unloading valve connected to the pressure-fluid inlet of the feed motor for quickly unloading the feed motor when a predetermined pressure decrease appears at the rotation motor as a consequence of a too large resistance against rotation of the drilling rod. There is also disclosed a device for keeping a pressure-fluid exhaust of the feed motor at an increased pressure through which the feed motor reverses when the unloading valve releases.

- United States Patent [191 v Ein et al. Apr. 9, 1974 DEVICE FOR CONTROLLING THE 408/9-1 l FEEDING FORCE AT ROCK-DRILLING [75] Inventors: Yrjii Armin Ein, Ektorp; Klas [56] References cued Goran Gunnarsson Ek, Tyreso; Karl v UNITED. STATES PATENTS Giista Bernhard Ekwall, 1,689,596 10/1928 Osgood 173/9 X Saltsjobaden; Eric Johan A d 2,459,902 1/1949 Tucker 173/8 X Engqvist Stockholm; Axe] Henry 2,905,441 9/1959 Poundstone. 173/8 Jfigerstrom, Vendelso; Sven 3,456,275 7/1969 Solomon 173/8 X W'lh N' k n s slogren dc a of Primary ExaminerErnest R. Purser Attorney, Agent, or Firm-Flynn & Frishauf [73] Assignee: Atlas Copco Aktiebolag, Nacka,

Sweden [5 7] ABSTRACT 22 Filed; Sept '5 1972 A device for controlling the feeding force at rock- 1 drilling is disclosed, comprising an unloading valve [21] Appl' N04 286,039 connected to the pressure-fluid inlet of the feed motor for quickly unloading the feed motor when a predeter- [30] Foreign Application P i it Dat mined pressure decrease appears at the rotation motor as a consequence of a too large resistance against ro- ZZ J' Z 2323:: tation of the drilling rod. There is also disclosed a device for keeping a pressure-fluid exhaust of the feed [52] Us. Cl. 173/8 408/1 1 motor at an increased pressure through which the feed 51 rm. Cl..2121:1:121:1111121111222:'..... 1251c 5/16 motor reverses when the filming valve releases- [58] .Field of Search 173/8, 9; 17 Claims, 7 Drawing Figures 4- /T T 1 H 112 DEVICE FOR CONTROLLING THE FEEDING FORCE AT ROCK-DRILLING The present invention concerns a device for controlling the feeding force at rock-drilling, through which jamming of the drilling rod in cracked rock is easily avoided by quickly connecting the pressure-fluid inlet of the feed motor to a low pressure when the drilling rod is exposed to such a large resistance against rotation that there is a risk that the drilling rod jams in the rock. To avoid jamming of the drilling rod it is essential that the feeding force applied against the drilling rod is very rapidly removed.

One aspect of the invention is based on the observation that the time for lowering the pressure in a vessel by a certain amount is shorter than the time for raising the pressure bythe same amount. A previously known control device of the above mentioned type (see US. Pat. Nos. 1,689,596 and 1,690,504) uses a pressure rise in the inlet of the rotation motor resulting from an increase in the resistance against rotation of the drilling rod for adjusting a valve, through which the feeding is reversed. According to this aspect of the present invention, however, a pressure decrease at the rotation motor is used for adjusting an unloading valve connected to the pressure fluid inlet of the feed motor.

A second aspect of the present invention concerns a device for controlling the feeding force at rock drilling by means of which the feed motor rapidly is brought to reverse if the resistance against rotation of the drilling rod becomes so large that a risk of jamming exists. This is achieved through keeping a pressure-fluid exhaust on the feed motor at an increased pressure through which reversal is obtained when an unloading valve connects the pressure fluid inlet of the feed motor to a low pressure as a consequence of a too large resistance against rotation of the drilling rod.

ln previously known control devices that make use of reversal of the feed motor a reversing valve is used. This control method is rather slow since the conduits that connect the reversing valve with the feed motor are exposed to comparatively large pressure changes at reversal.

According to the second aspect of the present invention a pressure-fluid exhaust is kept at an increased pressure and as a consequence supply of pressure-fluid for reversal of the feed motor is unnecessary. It has surprisingly turned out that a short reversal for control purpose can occur with a driving pressure which only is one-tenth to one-twentieth of that driving pressure which is required for pullingout the drilling rod from the drilled hole. The invention has the characteristics given in the subsequent claims.

The present invention is exemplified below with reference to the attached drawing in which FIG. 1 shows one realization of the invention.

FIG. 2 shows the realization according to FIG. 1 with a pneumatic regulator added in the inlet conduit of the feed motor.

FIG. 3 shows a modified form of pressure-sensing at the rotation motor.

FIG. 4 shows another realization of the invention.

FIG.'5 shows an alternate realization of that part of the device according to FIG. 4 which is limited by the line A.

FIG. 6 shows a way to achieve collaring with reduced feeding force after reversal.

reduced feeding force after reversal.

In the realizationaccording to FIG. 1 a pressure-gasdriven reversible vane motor 1 is used for rotating a not shown drilling rod. The motor 1 is supplied with pressure-gas from a magazine via a conventional startingvalve (not shown) through the conduit 2 and the inlet 30 at drilling. The motor 1, furthermore, comprises a main exhaust 31 and a residue exhaust 32. To the resi-v due exhaust 32 is connected a return conduit 3. When reversing the motor 1 the pressure-gas is connected to the motor in the opposite direction. For feeding of the drilling rod towards or from the rock a vane motor 4 of the same type as the motor 1' is used, at which the rotational movement of the motor 4 is transferred to the drilling rod for example by a chain in a conventional manner. The motor 4 may be substituted by a doubleacting jack. The motor 4 is supplied with pressure-gas through the conduit 5 and the inlet 35 at feeding of the drilling rod towards the rock. The motor 4. furthermore comprises a main exhaust 34 and a residue exhaust 33. A return-conduit 6 is connected to the residue exhaust 33. An unloading valve 7 is arranged in the inlet conduit 5. A conduit 15 is connected to the residue exhaust 32 of thev rotation motor 1 or to a special port 45 as shown in FIG. 3. The conduit 15 is also connected to a port 36 on a venting valve 9. A conduit 16 connects a port 37 on the venting valve 9 to a reciprocal valve 10. The venting valve 9 furthermore comprises a channel 38 which connects the port 37 to a hollow space 41 in which a valve member 40 is movable. The hollow space is via a port 39 connected to the surrounding atmosphere. The conduit 14 connects the reciprocal valve 10 to the unloading valve 7. The position of the valve member in the unloading valve 7 is controlled by the pressure in the conduit 14 and the force from an adjustable spring 8. A conduit 17 connects the reciprocal valve 10 to a valve 11. Furthermore a conduit 12 is connected to the valve 11 for supplying pressure-gas. Through adjustment of the valve 11 pressure-gas is supplied to the reciprocal valve 10 from the conduit 12 via the valve 11 and the conduit 17, through which the valve member of the reciprocal valve 10 is brought to a position opposite to that shown on the drawing. As a result, the pressurergas is conducted through the conduit '14 to the unloading valve 7, the valve member of which is brought to a position opposite to that shown on the drawing. This makes it possible to drive the feed motor 4 independent of the operating condition of the rotation motor 1.

In the realization according to FIG. 2 a regulator 18 and a venting valve 19 has been added to the realization shown in FIG. 1 in the supply conduit 5. Aconduit 20 is connected partly to the regulator 18 and partly to the conduit 14. Through this a continuous regulation of the feeding force is obtained when the resistance against rotation of the drilling rod is less than that resistance that causes adjustment of the unloading valve 7. The venting valve 19 has as its purpose to connect the conduit 5 to the atmosphere when the drilling rod is fed from the rock.

The control device according to FIG. 1 works in the following manner: if the resistance against rotation of the drilling rod increases, the number of revolutions of the rotation motor 1 decreases and as a result of this the pressure at the residue exhaust 32 decreases. As a 7 result of this the valve member 40 in the venting valve 9 is moved to the position shown on the drawing if the pressure decrease is not too slow. As a result of this the conduits 16, 14 are connected to the atmosphere via the port 37, the channel 38 and the port 39. Through this the pressure in the conduits 16, 14 is rapidly decreased to the pressure level which exists in the conduit 15. When the pressure in the conduit 14 has decreased to a value below a certain level which can be adjusted with the adjustable spring 8 the valve member in the unloading valve 7 is moved to the position shown on the drawing, through which the inlet 35 of the feed motor 4 is connected to the atmosphere. At the same time the conduit 5 is closed, through which unnecessary discharge of pressure-gas is prevented. To achieve maximum rapidity the port 36 on the venting valve 9 should be connected to the residue exhaust 32 of the rotation motor or the special port 45 through shortest possible conduit 15. If possible the conduit is excluded. Furthermore the unloading valve 7 should be connected as close to the inlet 35 of the feed motor 4 as possible.

The device according to FIG. 4 comprises a drilling machine 62 which includes a pressure-fluid-driven vane motor 1 for rotating the drilling rod 63 and a not shown percussion motor. The drilling machine 62 is mounted on a feeder 64 and is fed towards or from the rock by a pressure-fluid-driven vane motor 4 via a chain 65. The connections of the motors 1 and 4 to the drilling machine 62 and the feeding chain 65 are marked by the lines 60 and 61. The rotation motor 1 comprises a pressure-fluid inlet to which a supply conduit 2 for pressure-fluid is connected. The motor 1 furthermore comprises a main exhaust 31 and a residue exhaust 32 to which a return conduit 3 for pressurefluid is connected. If pressure-fluid is supplied through the conduit 3 instead of through conduit 2 reversed rotation of the motor 1 is achieved. The feed motor 4 which is of the same type as the motor 1 comprises a pressure-fluid inlet 35, a main exhaust 34 and a residue exhaust 33. At feeding of the drilling rod towards the rock the motor 4 is supplied with pressure-fluid through a conduit 50, the valve 52, a conduit 5 and an unloading valve 7 the valve member of which hereby takes a position opposite to that shown in FIG. 4. By means of a restricted connection 53 in the valve 52 and a spring loaded check valve 51 the residue exhaust 33 of the motor 4 is kept at an increased pressure. It has turned out to be suitable to use an increased pressure amounting to 0.2 0.4 atmospheres above the atmospheric pressure when using a certain motor 4. This pressure is surprisingly low since a pressure of 3-4 atmospheres above the atmospheric pressure is ordinarily required for pulling out the drilling rod from the drilled hole with the same motor 4. The pulling out of the drilling rod is achieved through bringing the valve member in the valve 52 to take a position opposite to that shown in FIG. 4 through which pressure-fluid is supplied to the motor 4 via the conduit 6. The above mentioned increased pressure is used for reversing the motor 4 which occurs when the unloading valve 7 is brought to take the position shown in FIG. 4, as a consequence of a pressure decrease in the conduit 14, through the action of the adjustable spring 8. An increasing resistance against the rotation of the drilling rod. 63 is sensed as a pressure decrease at the residue exhaust 32 of the motor 1. This pressure decrease is through a short conduit l5 transferred to a venting valve 9 the valve memher 40 of which takes the position shown in FIG. 4 when the pressure in the conduit 15 and the connection port 36 is lower than that in the channel 38. As a result the pressure fluid in the conduit 14 is conducted through the valve 10, the conduit 16, the port 37, the channel 38, the chamber 41 and the port 39 to a room where a pressure lower than that in the conduit 15 exists. Through this a rapid decrease of the pressure in the conduit 14 is obtained and thus a rapid reversal of the motor 4. If the valve member in the valve 11 is moved to a position opposite to that shown in FIG. 4 pressurefluid is supplied through the conduit 12, the valve 11 and the conduit 17 to the valve 10 the valve member of which through this action is brought to take a position opposite to that shown in FIG. 4. Through this the pressure-fluid is conducted through the conduit 14 to the unloading valve 7 the valve member of which is brought to take a position opposite to that shown in FIG. 4. As a consequence of this feeding of the drilling rod 63 towards or from the rock can occur independent of the operating condition of the rotation motor 1. The device shown in FIG. 4 is of course only an example. It is thus only a suitable measure to place the restricted connection 53 and the spring loaded check valve 51 in the same housing as the manual reversing valve 52. These devices may of course be placed anywhere if only they cause an increased pressure at the residue exhaust 33 of the feed motor 4. When the feed motor is hydraulically driven it is a suitable measure to place the restricted connection 53 and the spring loaded check valve 51 near the unloading valve 7. Through this an extra conduit for returning fluid from the unloading valve to the reservoir at pressure-controlled reversal can be avoided. This is achieved by using three check valves. One of them is connected in parallel with the spring loaded check valve 51 and reversely directed. The other two are connected for transferring fluid from the exhaust of the unloading valve 7 to the conduits 5 and 6. It is also possible to substitute the restricted connection 53 with a pressure accumulator connected to the residue exhaust 33 of the feed motor 4.

In FIG. 5 the vane motor 4 has been substituted by a jack 70.

FIGS. 6 and 7 show two ways to achieve collaring with reduced feeding force. Such collaring is many times suitable for reducing the risk of a renewed jamming tendency at collaring after release of the unloading valve 7. The ways shown in FIGS. 6 and 7 for achieving collaring with reduced feeding force do not, however, form any part of the present invention. In FIG. 6a variable restriction 81 and a check valve connected in parallel therewith has been arranged in the conduit 14 of the unloading valve 7. Through the restriction 81 a comparatively slow increase of the pressure in the pressure-fluid inlet 35 of the feed motor 4 is achieved when the resistance against rotation of the drilling rod 63 decreases and thus the pressure in the conduit 14 increases. Since the rate at which the pressure in the pressure-fluid inlet 35 increases is dependent on how rapid the pressure increases in that part of the conduit 14 which is situated between the restriction 81 and the unloading valve 7 the rate can be adjusted partly by the restriction 81 and partly by the volume of that part of the conduit 14 which is situated between the restriction 81 and the unloading valve 7. The check valve 80 has as purpose to short-circuit the restriction 81 at a pressure decrease in the conduit 14 through the unloading valve 7. In FIG. 7 a variable restriction 91 and a check valve 90 connected in parallel therewith has been arranged in the pressure-fluid-supply conduit 5 of the feed motor 4.

The above described and illustrated realizations are only to be regarded as examples which of course may be modified within the scope of the invention as defined in the appended claims.

What we claim is:

1. A device for controlling the feeding force at rockdrilling, comprising:

a pressure-gas-driven rotation motor adapted to be coupled to a drilling means,

a pressure-fluid-driven feed motor selectively feeding said drilling means toward the rock to be drilled, an unloading valve connected to a pressure-fluid inlet of the feed motor, and

sensing means for sensing a pressure at the rotation motor and for transferring said sensed pressure to the unloading valve, said unloading valve coupling the pressure-fluid inlet of the feed motor to a low pressure responsive to a predetermined decrease of said pressure at the rotation motor.

2. A device according to claim 1, comprising a regulator coupled to the pressure-fluid inlet of the feed motor and coupled to said rotation motor so asto be controlled by pressure changes appearing at the rotation motor.

3. A device according to claim 1 wherein said unloading valve couples said pressure-fiuid inlet to atmospheric pressure responsive to said decrease of pressure at the rotation motor, thereby reducing the drill feeding force of said feed motor.

4. A device according to claim 1 comprising additional pressure-fluid supply means selectively coupled to said unloading valve for selectively disabling said unloading valve and coupling said pressure-fluid inlet of said feed motor to its associated pressure-fluid supply independent of the operation of the rotation motor.

5. A device according to claim 1, in which said sensing means comprises a conduit means coupled to a residue exhaust of the rotation motor, for sensing the pressure of the substantially full-expanded pressure-gas in said rotation motor, said conduit means further coupled to the unloading valve.

6. A device according to claim 5, in which said sensing means comprises a venting valve arranged in said conduit means and arranged to connect a part of said conduit means to the atmosphere when the pressure in said part is higher than the pressure at said residue exhaust of the rotation motor.

7-. A device according to claim 6 wherein said venting valve includes'a hollow space with a movable. valve member slideable therein, a port connecting the hollow space with the atmosphere, and ports on opposite sides of said movable valve member coupled in said conduit means.

8. A device according to claim 6 including valve means coupled in said conduit means between said venting valve and said unloading valve and further selectively coupled to an additional pressure-fluid supply for selectively disabling said unloading valve and coupling said pressure-fluid inlet of said feed motor to its associated pressure-fluid supply independent of the operation of the rotation motor.

9. A device for controlling the feeding force at rockdrilling, comprising:

a pressure-fluid-driven rotation motor adapted to be coupled to a drilling means,

a pressure-fluid-driven feed motor selectively feeding said drilling means toward the rock to be'drilled,

an unloading valve connected to apressure-fluid inlet of the feed motor for selectively connecting said pressure-fluid inlet of the feed motor to a low pressure,

sensing means for sensing the resistance against rotation of the rotation motor and for transferring a signal corresponding to said sensed resistance against rotation to the unloading valve, and

means for keeping a pressure-fluid exhaust on the feed motor at an increased pressure such that reversal of the feed motor is obtained when the pressure-fluid inlet of the feed motor is connected to low pressure by the unloading valve.

10. A device according to claim 9, comprising a spring loaded check valve connected to said pressurefluid exhaust of the feed motor and a restricted connection between a pressure-fluid supply of the feed motor and said pressure-fluid exhaust.

11. A device according to claim l0, in which the spring loaded check valve is so arranged that said increased pressure constitutes an over-pressure which is less than one-tenth of the overpressure which is required for a long reversal of the feed motor.

12. A device according to claim 9 wherein said unloading valve couples said pressure-fluid inlet to atmospheric pressure responsive to said signal, thereby causing reversal of rotation of said feed motor.

13. A deviceaccording to claim 9, in which said sens- 15. A device according to claim 14 wherein said venting valve includes a hollow space with a movable valve-member slideable therein, a port connecting the hollow space with the atmosphere, and ports on opposite sides of said movable valve member coupled in said conduit means.

16. A device according to claim 14 including valve means coupled in said conduit means between said venting valve and said unloading valve and further selectively coupled toan additional pressure-fluid supply for selectively disabling said unloading valve and coupling said pressure-fluid inlet of said feed motor to its associated pressure-fluid supply independent of the operation of the rotation motor.

17. A device according to claim 14 comprising additional pressure-fluid supply means selectively coupled to said unloading valve for selectively disabling said un loading valve and coupling said pressure-fluid inlet of said feed motor to its associated pressure-fluid supply independent of the operation of the rotation motor. 

1. A device for controlling the feeding force at rock-drilling, comprising: a pressure-gas-driven rotation motor adapted to be coupled to a drilling means, a pressure-fluid-dRiven feed motor selectively feeding said drilling means toward the rock to be drilled, an unloading valve connected to a pressure-fluid inlet of the feed motor, and sensing means for sensing a pressure at the rotation motor and for transferring said sensed pressure to the unloading valve, said unloading valve coupling the pressure-fluid inlet of the feed motor to a low pressure responsive to a predetermined decrease of said pressure at the rotation motor.
 2. A device according to claim 1, comprising a regulator coupled to the pressure-fluid inlet of the feed motor and coupled to said rotation motor so as to be controlled by pressure changes appearing at the rotation motor.
 3. A device according to claim 1 wherein said unloading valve couples said pressure-fluid inlet to atmospheric pressure responsive to said decrease of pressure at the rotation motor, thereby reducing the drill feeding force of said feed motor.
 4. A device according to claim 1 comprising additional pressure-fluid supply means selectively coupled to said unloading valve for selectively disabling said unloading valve and coupling said pressure-fluid inlet of said feed motor to its associated pressure-fluid supply independent of the operation of the rotation motor.
 5. A device according to claim 1, in which said sensing means comprises a conduit means coupled to a residue exhaust of the rotation motor, for sensing the pressure of the substantially full-expanded pressure-gas in said rotation motor, said conduit means further coupled to the unloading valve.
 6. A device according to claim 5, in which said sensing means comprises a venting valve arranged in said conduit means and arranged to connect a part of said conduit means to the atmosphere when the pressure in said part is higher than the pressure at said residue exhaust of the rotation motor.
 7. A device according to claim 6 wherein said venting valve includes a hollow space with a movable valve member slideable therein, a port connecting the hollow space with the atmosphere, and ports on opposite sides of said movable valve member coupled in said conduit means.
 8. A device according to claim 6 including valve means coupled in said conduit means between said venting valve and said unloading valve and further selectively coupled to an additional pressure-fluid supply for selectively disabling said unloading valve and coupling said pressure-fluid inlet of said feed motor to its associated pressure-fluid supply independent of the operation of the rotation motor.
 9. A device for controlling the feeding force at rock-drilling, comprising: a pressure-fluid-driven rotation motor adapted to be coupled to a drilling means, a pressure-fluid-driven feed motor selectively feeding said drilling means toward the rock to be drilled, an unloading valve connected to a pressure-fluid inlet of the feed motor for selectively connecting said pressure-fluid inlet of the feed motor to a low pressure, sensing means for sensing the resistance against rotation of the rotation motor and for transferring a signal corresponding to said sensed resistance against rotation to the unloading valve, and means for keeping a pressure-fluid exhaust on the feed motor at an increased pressure such that reversal of the feed motor is obtained when the pressure-fluid inlet of the feed motor is connected to a low pressure by the unloading valve.
 10. A device according to claim 9, comprising a spring loaded check valve connected to said pressure-fluid exhaust of the feed motor and a restricted connection between a pressure-fluid supply of the feed motor and said pressure-fluid exhaust.
 11. A device according to claim 10, in which the spring loaded check valve is so arranged that said increased pressure constitutes an over-pressure which is less than one-tenth of the overpressure which is required for a long reversal of the feed motor.
 12. A device according to claim 9 wherein said unloading valve couples said pressure-fluId inlet to atmospheric pressure responsive to said signal, thereby causing reversal of rotation of said feed motor.
 13. A device according to claim 9, in which said sensing means comprises a conduit means coupled to a residue exhaust of the rotation motor, for sensing the pressure of the substantially full-expanded pressure-gas in said rotation motor, said conduit means being further coupled to the unloading valve.
 14. A device according to claim 13 in which said sensing means comprises a venting valve arranged in said conduit means and arranged to connect part of said conduit means to the atmosphere when the pressure in said part is higher than the pressure at said residue exhaust of the rotation motor.
 15. A device according to claim 14 wherein said venting valve includes a hollow space with a movable valve member slideable therein, a port connecting the hollow space with the atmosphere, and ports on opposite sides of said movable valve member coupled in said conduit means.
 16. A device according to claim 14 including valve means coupled in said conduit means between said venting valve and said unloading valve and further selectively coupled to an additional pressure-fluid supply for selectively disabling said unloading valve and coupling said pressure-fluid inlet of said feed motor to its associated pressure-fluid supply independent of the operation of the rotation motor.
 17. A device according to claim 14 comprising additional pressure-fluid supply means selectively coupled to said unloading valve for selectively disabling said unloading valve and coupling said pressure-fluid inlet of said feed motor to its associated pressure-fluid supply independent of the operation of the rotation motor. 